Rotary electric switch



Sept. 11, 1945. H. SMITH 2,384,652

ROTARY ELECTRIC SWITCH Filed July 21', 1945 Patented Sept. 11, 1945 ROTARY ELECTRIC swrrcn Hurley Smith, Bufialo, N. Y., assignor to Eric Electric Company, Inc., Buffalo, N. Y.

Application July 21, 1943, Serial No. 495,551

9 Claims.

This invention relates to switch mechanisms which are constructed to connect selected conductors. Switch mechanisms of this type may,

for example, be advantageously used in connecting the taps of transformers to yield different voltages, but it will be understood that it is not intended to limit this switch for use in connection with transformers.

One of the objects of this invention is to provide a rotary switch of improved and simplified construction.

A further object of my invention is to provide an improved switch construction which can be readily manufactured in various capacities.

A still further object is to produce a switch of this kind which, in its simplest form. includes one or more loops formed of flat spring strips secured to a central rotary post and which can be readily turned to move the loop or loops into eflicient sliding contact with different stationary contacts. It is also an object of this invention to provide the loops with contact shoes which are pressed into engagement with the stationary ccntacts by means of the resilient loops.

Other objects and advantages of th s invention will appear from the following description and claims.

In the accompanying drawing:

Fig. 1 is a fragmentary elevation of a rotary electrical switch embodying this invention.

Fig. 2 is a top plan view thereof, partly broken away, to show the interior of the switch.

Fig. 3 is a section through the central rotary post of the switch, having a flexible connectin band mounted thereon.

Fig. 4 is a side elevation of a switch of modified construction.

Fig. 5 is a fragmentary, sectional view of a movable connecting member of modified construction.

In the particular embodiment of the invention shown in Fig. 1, l0 represents the stationary conductors or contacts, any two of which may be connected by the movable switch member, and these conductors may be arranged in a circle and may be in the form of rods extending parallel to each other and supported in their operative positions in any suitable or desired manner, for example, by means of an insulating base H provided with suitable apertures through which the contacts extend. Any other means for hold ng the contacts in correct relation to the switch may be employed.

In the case of small switches, such as shown in Fig. 4, contacts l2 are provided which are relaturned.

tively short and which are held in place only by means of a base member l3 similar to the member ll shown in Fig. 1. If, however, the switches are of larger size and the contacts are relatively long, as shown in Fig. 1, preferably the upper ends thereof are secured to and held in place in any suitable manner, for example, by a disk 14 of insulating material. The contacts may be secured to the base insulating member H in any suitable or desired manner, those shown in Fig. 1 having the lower portions thereof which extend throu h the base II of reduced diameter and having their lower extremities l5 threaded and provided with nuts i6 by means of which the contacts are secured to the base member II. In order to connect the terminals or conductors (not shown) leading to the switch member, to the contacts [0, another nut 11 is preferably provided on a threaded'portion I5 of each stationary contact It, so that the conductors may be secured to the contacts in the usual manner.

. The movable part of the switch includes a central post or shaft 20 which may be made of any suitable or desired material and which is arranged centrally with reference to the contacts or rods 10 and is rotatably mounted in the base member II and in the insulating disk 14. This central shaft may be held against endwise movement relative to the base in any suitable manner. for example, by means of split spring rings 2| gripping the central shaft and arranged one above and the other below the base II. This shaft is provided at its upper end with a knob or hand wheel 22 of any suitable or desired construction, by means of which the shaft can be While I have shown the hand wheel 22 arranged in close proximity to the upper disk l4, it is obvious that the shaft 20 may be elongated so that the knob may be located at a considerable distance from the switch if such spacing is desired to facilitate the operation of the switch. The shaft 20 is preferably, though not necessarily, made of insulating material.

In order to connect any two adjacent contacts In with each other, I provide in the construction shown in Figs. 1 to 4 one or more flexible and resilient current conducting members made of a strip of metal which is both resilient and a good conductor of electricity. Certan copper alloys are well suited for this purpose, such for example as beryllium copper, but as will be hereinafter explained, all portions of the connecting bands need not be of conducting material but must be resilient to urge a conducting member into good electrical contact with the contact posts or rods [0.

In the construction shown in Fig. l, I have shown two such movable resilient contacts or conductors 25 which are preferably made of flat strips or bands of resilient material in loop form. Each of these movable contacts may, for example, be made from a flat strip of material which is bent to form a loop and then secured to the central post or shaft 20, or if desired, these movable conductors may be made of an endless ring of this resilient material. Fig. 3 shOWs a band or contacting member 25 when mounted on the central shaft 29 and free to assume its normal shape, and 2 shows the same strip when arranged within the switch and in engagement with two contacts l0, showing how the band is deflected out of its normal shape so that it bears against the contacts [0.

The bands 25 may be secured to the central shaft in any suitable or desired manner, and in the particular construction illustrated by way of example, the central post or shaft is provided with a longitudinal slot 21 extending from the lower end thereof upwardly approximately to the insulating disk M. The ends of the resilient band 25 may be inserted into the slot and are preferably apertured to receive a bolt or pin 28 which may extend through a hole in the shaft 20, The bolt or pin 28, in the construction shown, is held in place by means of a cotter pin 29. Consequently, the resilient movable contact members 25 are free to assume their normal, substantially circular positions when secured to the shaft 20 and may be flexed into a substantially oval or elliptical shape, as shown in Fig. 2, when assembled in a switch. Any desired number of these resilient bands may be mounted on the shaft 20, only two being shown in Fig. 1.

The contact bands 25 must be held on the central post with sufllcient rigidity so that they will extend outwardly from the post substantially at a ri ht angle thereto. These bands by being pressed into oval shape, exert a pressure outwardly from the central shaft 29 against the stationary contacts In and this pressure serves to urge the portions which engage the contacts in into engagement with these contacts along their entire widths. In other words, if a band, such as shown in Fig. l, were not entirely horizontal and would tend to engage the contacts I only at its upper or lower edge, the outward pressure on the band would cause the band to become distorted sufficiently to engage each of the contacts I 0 on a line extending throughout the entire Width of the band, thus forming excellent current conducting contacts with the contact members I0,

When it is desired to change the tap connections, the knob or hand wheel 22 is turned, which causes the loop or loops to be deflected inwardly so that they slide past a contact, and the loops then again become bowed outwardly as they move into engagement with other contact members In. This expansion of the loops causes them to hold themselves resiliently in the desired position of engagement with two contact members It]. The knob or hand wheel may be provided with suitable index means, such for example as an arrow 30, which enables the position of the hand wheel relatively to the stationary contacts to be determined, and suitable index devices (not shown) may also be employed to indicate the location of the stationary contact members.

In the smaller switch shown in Fig. 4, a central shaft 35 is provided with a resilient contacting band 36 which may be secured to the shaft in the same manner as described in connection with Figs. 1 to 3, the shaft 35 being provided with a slot 31 and a hand wheel or knob 38. The stationary contact members l2 are relatively short and are, consequently, held in place by means of the insulating base member I3, and the lower ends of these contact members may be provided with apertures 39 in which the conductors may be soldered or otherwise secured. The operation of the smaller switch is identical with that of the larger one shown in Figs. 1 to 3.

As has been stated, it is not necessary that the looped member of the movable contact be also the current-carrying member, and in Fig. 5, I have illustrated a movable contact member of modified construction having a resilient loop 40 which may be made of steel or other material and to which a, contact shoe 4 I may be suitably secured in any desired manner. This movable shoe is preferably made of a metal which is a good conductor of electricity and is shaped so that it may readily contact with two adjacent stationary contact members ID. The resilient loop 40 may be made of a single strip of flat metal, as described in connection with Figs. 1 to 3, and may be secured to th shaft 20 in the same manner. This spring member urges the contact shoe 4| against the stationary contacts and when the movable member is moved for engagement with the other contacts, the loop member 40 is compressed or flattened as the shoe 4i rides upon a single stationary contact member, and again expands as the shoe seats into engagement with two adjacent stationary contacts, this action on the part of the shoe and loop being due to the fact that the radius of curvature of the shoe and of the flattened loop is less than the radius of the circle passing through the stationary contact members. This looped member also urges the contact shoe into line contact with the stationary contact members I0.

I claim as my invention:

1. A rotary electric switch comprising a plurality of stationary contact members arranged about an axis, a shaft rotatable about an axis substantially coinciding with said first mentioned axis, and a movable contact member secured to said shaft and including a loop of resilient material having one portion thereof secured to said shaft for holding said material in loop form and yieldingly urging another portion thereof by its own resilience toward a pair of said stationary contact members, to form an electrical connection between said stationary members, said loop exerting pressure against said stationary contact members, and being deflected upon turning said shaft to mOVe said loop from one pair of contacts to another.

2. A rotary electric switch comprising a rotary shaft, a plurality of stationary contact members arranged about; said shaft substantially equidistant therefrom, and a movabl contact member secured to said shaft and comprising a loop of resilient material having one portion thereof rigidly secured to said shaft, and having another portion thereof extending outwardly from a side of said shaft and formed for connecting any two adjacent stationary contact members and to yield upon turning of said shaft to pass from one pair of stationary contacts to another pair.

3. A rotary electric switch according to claim 2, in which said loop is formed of a flat strip of resilient material bent into p form and having its ends secured to said shaft to hold said material in loop form.

4. A rotary electric switch according to claim 2, in which said loop is formed of a flat strip of resilient current-conducting material formed to engage any two adjacent stationary contact members and to slide along said stationary contact members when said shaft is turned to move said loop from one pair of stationary contact members to another.

5. A rotary electric switch comprising a rotary shaft, a plurality of stationary contact members arranged about said shaft substantially equidistant therefrom, a movable contact member secured to said shaft and comprising a loop of resilient material having one portion thereof rigidly secured to said shaft, and a contact shoe secured to the opposite portion of the loop and :formed to connect a pair of adjacent stationary contacts and yieldingly pressed into engagement with said stationary contacts by said loop, said shoe being slidable into engagement with different pairs of stationary contacts through the medium of said loop when said shaft is turned.

6. A rotary electric switch comprising a plurality of stationary contact members arranged about an axis, a shaft rotatable about an axis substantially coinciding with said first mentioned axis, a shoe of conducting material of sufficient length to contact two adjacent stationary contacts and formed to slide crosswise of said contacts to engage different pairs of contacts, and a loop of resilient material having one portion thereof secured to said shaft and having said shoe secured to a substantially diametrically opposite portion thereof, for transmitting rotary motion of said shaft to said shoe.

7. A rotary electric switch comprising a plurality of stationary contact members arranged about an axis, a shaft rotatable about an axis substantially coinciding with said first mentioned axis and having a substantially longitudinally extending slot, and a movable contact member comprising a loop formed of flat strip material and extending through said slot and secured to said shaft to move about the axis of said shaft when said shaft is turned and for holding said strip material in loop form, said loop being movable by rotation of said shaft into circuit closing relation to different pairs of adjacent stationary contact members.

8. A rotary electric switch comprising a rotary shaft, a plurality of stationary contact members arranged about said shaft substantially equidistant therefrom and a plurality of movalble contact members mounted on said shaft and each comprising a loop of resilient material having a circumferential portion thereof secured to said shaft ifOl' holding said resilient material in p form and for causing said loops to move about the axis of said shaft when said shaft is turned, all of said loops extending outwardly from said central shaft in the same direction, said loops being of such diameter as to exert pressure toward said stationary contacts due to their own resilience and having current conducting portions formed to connect two adjacent stationary contacts, said shaft when rotated sliding said loops from one adjacent pair of stationary contacts to another pair.

9. A rotary electric switch comprising a plurality of stationary contact members in the fonm of rods of conducting material arranged about an axis, an insulating disk on which said rods are mounted in parallel relation to each other and to said axis, a shaft rotatable about an axis substantially coinciding with said first mentioned axis, and a movable contact member secured to said shaft and comprising a loop of resilient material of substantially reater width than thickness and having one portion thereof secured to said shaft and yieldingly urging another portion thereof by its own resilience into engagement with said rods, said loop being sufficiently flexible to produce line contacts of said other portion with said rods, said loop being yieldable to permit turning of the shaft to move said loop from one pair of contacts to another.

HURLEY SMITH. 

